1. Field of the Invention
This invention relates to a video signal reproducing apparatus for reproducing a video signal.
2. Description of the Related Art
Video tape recorders include a kind having a camera combined in one body therewith (hereinafter referred to as a camera-combined VTR). In cases where the camera-combined VTR is arranged to use a solid-state image sensor for the camera part, a video signal produced from the camera part would deteriorate due to a drop-out if there is some flaw among picture elements arranged on the image sensing plane of the solid-state image sensor. In the event of a video signal obtained from such faulty picture elements, therefore, it has been practiced to lessen the deterioration by means of a picture element defect compensating circuit. The compensating circuit is arranged to replace a faulty video signal portion obtained from the image sensor with a normal video signal portion which is obtained one horizontal scanning period (hereinafter referred to as H period) before and is delayed through a delay circuit.
In reproducing a video signal recorded on a magnetic tape which is employed as a record bearing medium with the VTR, occurrence of a drop-out in a reproduced video signal also deteriorates the reproduced video signal. The reproducing part of the VTR is, therefore, arranged to detect the occurrence of a drop-out in the video signal reproduced by a magnetic head from the magnetic tape. In the event of occurrence of a drop-out in the reproduced video signal, a faulty signal portion thus obtained is replaced by a drop-out compensation circuit with a normal signal portion which has been reproduced one H period before without any drop-out and delayed by a 1-H delay circuit.
Further, the camera part of the conventional camera-combined type VTR has been arranged to convert the optical image of an object picked up into a video signal; to display the image of the object at an electric view finder (hereinafter referred to as EVF) or on an external monitor by supplying the video signal to the EVF or the monitor via an external output terminal; and to record the video signal on a magnetic tape by means of a rotary magnetic head or the like by supplying the video signal to the recording part of the VTR. Meanwhile the reproducing part of the VTR has been arranged to process a reproduced video signal including a drop-out compensating process, an edge emphasizing process, a noise removing process, etc.; and then to have an image displayed on the basis of the reproduced processed video signal by supplying it to an external monitor TV set or the like from an external output terminal.
In recording, on a magnetic tape, a color video signal obtained by means of a camera, if the white balance is not adequately obtained, the color of a reproduced picture tends to become unnatural when the color video signal is reproduced from the magnetic tape. In view of this, the conventional camera-combined type VTR has been arranged to include a white balance obtaining circuit in a video signal processing circuit of the camera part thereof.
Further, in recording, R, G and B signals which are obtained at the camera part of the camera-combined type VTR are supplied to a matrix circuit to obtain a luminance signal Y and color difference signals R-Y and B-Y. A character luminance signal which is generated by a character generator is added to the luminance signal Y. The luminance signal then undergoes a signal processing operation including pre-emphasis process, etc. before it is frequency modulated. Meanwhile, the color difference signals R-Y and B-Y are quadrature two-phase modulated into carrier chrominance signal. Then, a character carrier chrominance signal which is generated also by the character generator is added to the carrier chrominance signal among other processes performed on the chrominance signal. After these processes, the chrominance signal is low band converted into a low-band carrier chrominance signal. The frequency modulated luminance signal and the low-band converted carrier chrominance signal are frequency multiplexed and made into a recording signal to be recorded on the tape by means of the rotary head.
During reproduction, a reproduced signal is supplied to the low-pass filter and a bandpass filter to separate the frequency modulated chrominance signal and the low-band converted carrier chrominance signal. The frequency modulated luminance signal is demodulated into the original luminance signal. The low-band converted carrier chrominance signal is frequency converted into the original carrier chrominance signal. Then, the luminance signal and the carrier chrominance signal are multiplexed and produced as a television signal.
Further, the camera part of the conventional camera-combined type VTR includes a high luminance suppression circuit which is arranged to prevent a false color signal from appearing in the event of a high degree of luminance by suppressing a luminance signal to have no chrominance signal mixed therein. Further, during reproduction, a drop-out, a noise, etc. would affect a color burst signal included in the reproduced video signal and would cause it to be reproduced either as a drop-out signal or as a false signal. In that event, a reproduced picture based on a video signal having such a color burst signal becomes hardly presentable. To solve this problem, therefore, the reproduction system of the VTR includes a so-called color killer circuit which is arranged to cut a reproduced chrominance signal as necessary according to the level of the reproduced color burst signal. Meanwhile, a higher degree of resolution is obtainable in a black-and-white mode (hereinafter referred to as B/W mode) which gives a broader band of the luminance signal. Therefore, picture recording is sometimes performed intentionally in the B/W mode. In view of this, the reproduction system of the conventional VTR is sometimes provided with a circuit which is arranged to discriminate a picture recorded on a magnetic tape as to whether it is recorded in the B/W mode or in a color mode; and, in the event of the former, to cut the chrominance signal, because: In the case of the B/W mode, a signal component of a chrominance signal band is either meaningless or rather detrimental and therefore should be prevented from mixing in the luminance signal.
The conventional camera-combined type VTR is arranged to emphatically record the edge parts of the recording video signal by applying a luminance signal produced from the image pick-up and recording camera part to a luminance signal edge emphasizing circuit; and, for a reproduced signal obtained from the VTR part thereof, to emphasize the edge parts of a reproduced luminance signal separated from the reproduced signal by means of another luminance signal edge emphasizing circuit in the stage of adding up the reproduced luminance signal and a reproduced carrier chrominance signal. In other words, the conventional camera-combined type VTR has been provided with an edge emphasizing circuit for the recording signal and another edge emphasizing circuit for the reproduced signal. Further, the conventional camera-combined type VTR is provided with a fader device which is arranged within the camera part. However, no fader device is provided for the reproduction system of the VTR. Therefore, in a case where a fading process is to be applied to a reproduced video signal, some video editing device or the like that is capable of functioning as a fader must be connected to the video output terminal Vout. The conventional camera-combined type VTR has been thus arranged to be capable of forming a video signal by using a fader before transmitting it to the VTR part during recording. In reproducing a recorded video signal, the above stated video editing device has been used when a fading process is to be applied to the reproduced signal.
However, the camera-combined type VTR is required to be small in size and light in weight in general. Whereas, the above stated picture element defect correction circuit and the drop-out correction circuit of the camera-combined type VTR are discretely provided with separate 1-H delay circuits although these correction circuits are never simultaneously used. This arrangement not only hinders reduction in size and weight of the VTR but also results in an increase in cost.
The conventional camera-combined type VTR is arranged to record on a magnetic tape, without any noise removing process, a video signal formed on the basis of an optical image of an object obtained from the camera part; and to perform a noise removing process during a reproducing operation. According to this method, however, the noise component generated at the camera part during a recording operation cannot be removed and thus has a deteriorated reproduced picture displayed on an external monitor TV set although a noise component generated at the time of reproduction from the magnetic tape can be removed.
Further, since no noise removing process is performed in recording at the camera part of the camera-combined type VTR, the picture displayed on the above stated EVF or the external monitor TV set has not been always adequately obtained. This problem may be solved by providing the camera part of the VTR with a noise removing circuit or the like in addition to the circuit provided within the reproducing part. However, for the camera-combined type VTR which is strongly desired to be compact in size and light in weight, the arrangement to provide the camera part with additional noise removing circuitry which is never used concurrently with the noise removing circuit of the reproducing part not only hinders reduction in size and weight but also results in an increase in cost.
In recording a color video signal on a magnetic tape, it is absolutely necessary to make white balance adjustment. Meanwhile, the white balance of the monitor TV set also has a considerable degree of influence over the reproduced picture. It is therefore preferable to include a white balance adjusting process in reproducing the video signal from the magnetic tape. The conventional camera-combined type VTR has been arranged without including any white balance circuit in the reproducing circuit system thereof on the assumption that the white balance is adequately adjusted during a recording operation and that the monitor TV also has adequate white balance.
It is, however, not desirable to have an additional white balance circuit solely for the reproduction part because it increases the number of circuit elements and the manufacturing cost of the camera-combined type VTR which is strongly desired to be compact and not heavy.
In case that the camera-combined type VTR is to be arranged to add to the picture some character or characters indicating a title, a date, etc., a character video signal has been added by means of a character generator included in the camera part to the color video signal obtained by the camera part by sensing an object's image. The addition of the character video signal has been possible only during a recording operation. In cases where characters must be added during a reproducing operation, the VTR necessitated use of some discrete editing device or the like having a character adding function. Such a device makes the VTR system complex and expensive. This has presented a problem.
Another shortcoming of the conventional camera combined type VTR resides in that: In correcting the chrominance signal during a reproducing operation, the chrominance signal must be corrected in the state of the carrier chrominance signal. However, since the carrier chrominance signal includes hue information by its phase, it is difficult to correct it while retaining the continuity of the phase variations thereof. Any phase relation disturbing correction, such as compensation for a signal drop-out or noise removal by means of a feedback type noise removing circuit, has been impossible. This difficulty has inevitably resulted in some deterioration, such as color shading, of a reproduced chrominance signal.
The high luminance suppressing circuit and the color killer circuit restrain the addition of the chrominance signal to the luminance signal. The conventional camera-combined type VTR is provided with both of these circuits. The high luminance suppressing circuit is arranged to be used for an image sensing operation while the color killer circuit is used for reproduction. However, the use of both of these circuits performing similar functions is wasteful and meaningless for the camera-combined type VTR which is strongly desired to be small in size and light in weight.
Further, the conventional camera-combined type VTR is provided, as mentioned in the foregoing, with the edge emphasizing circuit for the recording signal and another edge emphasizing circuit for the reproduced signal. Meanwhile, the arrangement to provide the camera-combined type VTR which is strongly desired to be compact and light with both the emphasizing circuits which perform the same function for recording and reproduction and not to be simultaneously used is likewise meaningless.
It is the most important advantage for a camera combined type VTR to be easily portable and to be capable of permitting confirmation of a recording state at the very place of recording immediately after recording. Therefore, it is a disadvantage and not desirable for the VTR of this type to necessitate the use of a discrete video editing device having a fading function even if the device is small in size.
In view of this, it is conceivable to solve the above stated problem by including a fader device in the reproduction system of the VTR of this type in addition to the fader device provided within the camera part thereof. In that event, however, the circuit arrangement of the VTR becomes complex causing an increase in the manufacturing cost. That presents another problem.